ant," respectively. Loudness, noisiness, and annoyance were grouped under
the "powerful" factor. Therefore, loudness, noisiness, and annoyance cannot be regarded as independent of each other. Naturally they are not
identical, but the highest correlation is obtained between loudness and
Leq. On the other hand, noisiness and annoyance judgments exhibit systematic deviations from a linear relation. For example, music was judged
less noisy and less annoying than the other sound sources. The results
found in Fig. 16.3 are reinforced by the results of this experiment. The
results of Experiment 4 suggest that sound level has the greatest effect on
noisiness and annoyance judgments, but that other factors such as sound
quality and subjective meaning have some effect as well ( Kuwano,
Namba,
&
Fastl, 1988). These results also suggest that loudness judgments may be
affected by the impression of noisiness or annoyance of the sounds.

CONCLUSIONS

1.

A ratio scale was found between Leq and loudness when the loudness
of various kinds of actual, non-steady-state sounds was judged by the
method of magnitude estimation. However, when the loudness of the same
stimuli was judged by category scaling, a logarithmic scale was obtained.

2.

Using the method of "scale discrimination," a 10-dB step size was
found to produce equal perceived ratios and a 3-dB step size was found
to produce equal perceived interval. These findings support the notion that
the sone scale is a ratio scale. On the other hand, they suggest that an
equal interval in decibels does not always produce the perception of an
equal ratio.

3.

To avoid the ambiguity of a sensory scale (whether it is an equal
ratio or equal interval scale), it is preferable to use PSE. PSEs calculated
from magnitude estimation were found to be similar to PSEs obtained by
the method of adjustment. Therefore, these results suggest that if the
dynamic ranges are equal, PSEs can be obtained easily and quickly for
heterogeneous sounds from magnitude estimation.

4.

There was some variation in the slope of the power function for
loudness among nine different noise sources. No physical factors were
found to explain the differences. Using the semantic differential method,
the timbre of the same stimulus set was judged. The results suggest that
unpleasant impressions of sound (noisiness or annoyance) may affect loudness judgments when actual sounds are used as stimuli. The validity of the
judgment, that is, what is judged in the experiment using actual sound
sources, should be examined carefully from various perspectives using a
variety of methods.

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